Markers in the polytene chromosomes of freshwater Chironomus Meigen (Diptera, Chironomidae) species Author Michailova, Paraskeva text Zootaxa 2024 2024-05-22 5453 4 511 537 http://dx.doi.org/10.11646/zootaxa.5360.3.8 journal article 10.11646/zootaxa.5453.4.3 1175-5326 11239735 B535A3FF-151C-4070-9BE7-2FE6E3238847 Chironomus parathummi Keyl The species has the chromosome set 2n = 8. Chromosomes AC and BF are metacentric, DE chromosome is submetacentric, the chromosome G is telocentric ( Fig. 20 AB ). The centromere regions of all chromosomes are thin dark bands. Chromosome G has one NOR located near to the centromeric region and two BRs. Chromosome homologues are partially unconjugated. The marker of the species are the pair of dark bands located in the middle of the chromosome G and the three dark ones between them ( Fig. 20B ). The species is monomorphic, without chromosomal aberrations. However , many active regions-puffs (P) are found along the length of the chromosomes. Five larvae were analyzed . Collection sites : Burgas : Atanasovsko Lake , Varna , Shabla Lake . FIGURE 20 (AB) . Polytene chromosomes of Chironomus parathummi . The numbers on the chromosome arms indicate the “basic”sequences. The large arrows show the localization of the centromere region. The small arrow on chromosome G indicates the marker sequences required for species identification. BR—Balbiani Ring, NOR—Nuclear Organizer Region. A, B, C, D, E, F, G—arms of the chromosomes. Scale bar, 10µm. FIGURE 20 (B) . Figure continued. Lacunarius cytocomples with chromosome arm combinations: AD BC EF G.